Following neoadjuvant chemotherapy for osteosarcoma, the resected specimen shows > 90% tumour necrosis. This histological response is graded as Huvos Grade IV. What is the clinical significance of this finding?
- A No impact on survival; surgical margins are the only prognostic factor
- B Good histological response; associated with improved 5-year event-free and overall survival ✓
- C Indicates resistance; mandates switch to second-line salvage chemotherapy regimen
- D Predicts increased risk of local recurrence despite adequate resection margins
Correct answer: B. Good histological response; associated with improved 5-year event-free and overall survival
Explanation
The Huvos grading system quantifies tumour necrosis in resected specimens after neoadjuvant chemotherapy: Grades III and IV (> 90% necrosis) signify good response and are strongly associated with improved event-free and overall survival. Good responders continue the same adjuvant regimen. Poor responders (< 90% necrosis) may undergo protocol modification, though benefit of switching is debated. Surgical margin remains independently prognostic.
Reference: Maheshwari Essential Orthopaedics, 6th ed.
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